The world as a whole? Kind of depends. Elves, yes - they've got a heck of a lot of time on their hands, writing is a great way to communicate over long distances when you don't have electricity, so no reason not to. Dwarves, yes - similar reasons. Halflings, gnomes, probably. Humans ...

... that's where things get difficult. Relatively short lives, the farmers need their kids working, and so forth, versus the advantage of being able to keep accounts, enter into written agreements, read the postings, and so forth, and so forth. The problem there is that literacy undermines power: you can't lie to people who can read when they can read the law or the holy book or the contract themselves. So, if the culture is modeled on an absolute monarch and a powerful nobility lording it over relatively powerless serfs and peasants, then no, not much literacy there. If the culture is more a Roman or Greek or Renaissance model, then yes, quite a bit of literacy, it's how you keep from getting ripped off. If the world is big enough to have both types represented, then you've got some areas with high literacy and others with very little. Mine is mixed. I've got frontier areas that depend pretty heavily on carrier pigeons and post riders.